The invention relates to mounting clamps for tubing and in particular to tube clamps for hydraulic tubing used in environments which can cause wear between tube and clamp.
Clamps of the character indicated are used in aircraft construction, for support of hydraulic tubing in various environments, involving for example relatively great longitudinal displacement as in the course of wing flexure, lesser longitudinal displacement as in the case of vibratory oscillation, and elevated temperature as in the vicinity of an engine. These are among the problems addressed in U.S. Pat. No. 4,006,874, to which reference is made for a more complete discussion. And reference may also be had to the patents cited in prosecution of said U.S. Pat. No. 4,066,874, for prior art against which to evaluate the background.
In particular, said U.S. Pat. No. 4,006,874 purports to solve the indicated problems by so devising the frictional engagement of a split sleeve to a tube, in the context of support-clamp engagement to the sleeve, that less friction characterizes the latter engagement than is the case for the sleeve-to-tube engagement. The sleeve has raised end shoulders between which the clamp-to-sleeve engagement is preferentially displaceable, yet in the case of unusual need, the clamp will engage one of the shoulders to displace the sleeve on the tube. In practice, the friction of sleeve-to-tube engagement is not enough to provide real assurance against sleeve wear on the tube, and integrity of the hydraulic system is accordingly threatened. Also, in the relatively high-heat environment of an engine, no sleeve displacement on the tube can ever be tolerated; in this latter situation, it has become the practice to braze the sleeve to the tube, an expensive practice which severely limits maintenance in the field.